Geology Test 2

Front 1

How many barrier islands form the outer portion of the Georgia Coast?

Back 1

12 barrier islands

Front 2

According to Griffin and Henry erosion rates are among the highest on what Georgia Coast island?

Back 2

St. Catherine's Island

Front 3

The high erosion rates off St. Catherine's Island can be attributed to what factors?

Back 3

Greatest distance from rivers with significant discharge
Head of the Georgia Bight
Impoundment of the Savannah River and the dredging of its river channel
Sea level rise of 2.9mm/yr estimated from tide gauge data.

Front 4

Georgia Coast is

Back 4

full of Sediment Supply

Front 5

sediment supply to the Georgia coast has been ______ with increase in sediment supply

Back 5

dynamic

Front 6

What causes the dynamic increase in sediment supply

Back 6

land clearing and management practices following the development of agriculture in 1800's until the 1920's

Front 7

a decrease in sediment supply is associated with

Back 7

the placement of impoundments or dams in the 20th century.

Front 8

A/an _____ is noted in the shoreline retreat in berm/spit landforms at St. Catherines Island that appears to correlate with the placement of the initial dams on the Savannah River in 1952.

Back 8

acceleration

Front 9

Deserts cover __ of land surfaces

Back 9

25%

Front 10

The primary control on deserts

Back 10

Plate tectonics

Front 11

Unique and lovely deserts are characterized by

Back 11

Extreme dryness (hot or cold)
Specialized ecosystems
low human populations
unique geologic processes
land that is arid

Front 12

Evaporation prevents ___, due to the extremeness of aridity of the land

Back 12

permanent surface water

Front 13

Vegetation cover less than __ of its surface

Back 13

15%

Front 14

Annuanl rainfall amounts to less than ____ per year

Back 14

10 inches or 25 cm

Front 15

True or False: Desert types in only hot environments

Back 15

false: deserts exist in hot and cold environments

Front 16

Hot deserts form in what environment

Back 16

Low latitudes
Low elevations
Far from oceans

Front 17

Cold deserts form in what environment

Back 17

High latitudes
High elevations
Near cold ocean currents

Front 18

Five types of deserts

Back 18

Subtropical
Rain-shadown
Coastal
Continental
Polar

Front 19

typical hot deserts in America

Back 19

Mohave
Chihuahan
Sonoran

Front 20

Only cold desert in America

Back 20

Great Basin Desert

Front 21

Largest deserts on the earth

Back 21

Subtropical deserts

Front 22

Subtropical deserts form due to patterns of

Back 22

atmospheric convection

Front 23

Atmospheric convection

Back 23

Equator-0 degree latitude
Solar energy evaporate water, which rises as hot, moist air
Rising air cools and expands, dropping abundant rain on the equatorial rain-forests
This air, stripped of moisture, flows to the north and south.
The air, stripped of mois

Front 24

Subtropics

Back 24

20 degree to 30 degree north to south
Cool, sinking air wicks water from the surface
The air heats up and the landscape dries out

Front 25

African deserts bracket the equator in the

Back 25

subtropical regions

Front 26

northern African subtropical deserts

Back 26

Saharan and Arabian

Front 27

What straddles the equator in Africa?

Back 27

rainforest

Front 28

southern African subtropical deserts

Back 28

Namib and Kalahari

Front 29

Rainshadow deserts

Back 29

Moist ocean winds are driven up and over mountains
Windward air is forced to rise, expand, and cool.
Moisture condenses, rains fall, which create a rain forest
Leeward air, stripped of moisture, sinks toward the surface.
Sinking air warms, compresses, absorbs water from land
Dry arid region forms.
North American (Northern Oregon)

Front 30

Coastal Deserts

Back 30

Cool are over cold ocean water holds little moisture
The air absorbs moisture when it interacts with land

Front 31

Coastal desert location

Back 31

Atacama Desert (Peru), driest place on Earth

Front 32

Continental interior deserts

Back 32

Air loses moisture as it crosses continents
LAnd far from ocean moisture can be very dry.

Front 33

Location of interior desert

Back 33

The Gobi desert

Front 34

Polar deserts

Back 34

Above 66 degrees N and S latitudes where there is little air moisture
Air circulation carries dry air to polar regions
IT is so cold that the air can't hold moisture

Front 35

True or False: Physical weathering dominates deserts

Back 35

true: the soils are thin.

Front 36

true or false: the horizons in deserts are poorly defined

Back 36

true

Front 37

Exposed surfaces develop ____

Back 37

desert varnish

Front 38

desert varnish

Back 38

dark surface coating of iron and manganese oxides
forms very slowly from bacterial activity, dust, and water.
Native americans carved petroglyphs in desert varnish

Front 39

Alluvial fans

Back 39

conical acumulations of sediment
Water exiting a canyon spreads out and drops sediment

Front 40

How do alluvial fans grow?

Back 40

outward from source over time

Front 41

Sediment characteristics of an alluvial fan near a source

Back 41

coarse sediments

Front 42

Sediment characteristics of an alluvial fan away from a source

Back 42

finer sediments

Front 43

Bajadas

Back 43

Alluvial fans coalesce along a mountain front

Front 44

Surface load

Back 44

wind carried
coarse, sand sized particles

Front 45

Suspended load

Back 45

finer- grained, silt sized "dust"

Front 46

True or false: silt forms dunes inside deserts

Back 46

false: sand forms dunes.

Front 47

Sand seas

Back 47

Vast ares of dunes

Front 48

Dunes

Back 48

Windblown accumulations of sand
over time, a dune grows and begins to move downwind

Front 49

Sand ____ up windward side

Back 49

saltates

Front 50

Sand ___ down the slip face

Back 50

tumbles

Front 51

Gigantic oceans of sand

Back 51

ergs

Front 52

Where are ergs located

Back 52

Arabian Peninsula
Namibia Desert

Front 53

Weathering

Back 53

the disintegration, or breakdown of rock material.

Front 54

Mechanical Weathering

Back 54

no change in chemical composition, just distegration into smaller pieces

Front 55

What cause physical breakups of rocks

Back 55

pressure release
water: freeze and thaw cycles
crystallization of salt in cracks
thermal expansion and contraction

Front 56

Physical breakup increases ____

Back 56

the total surface area exposed to weathering processes.

Front 57

Chemical Weathering

Back 57

breakdown as a result of chemical reactions.
transformation/ decomposition of one mineral into another.

Front 58

Mineral breakdown

Back 58

carbonate dissolves
primary minerals change into secondary minerals (mostly clays)

Front 59

True or False: water is the main agent/operator in chemical weathering

Back 59

true

Front 60

Dissolution

Back 60

Many organic and ionic compounds dissolve in water

Front 61

What compounds dissolve in water

Back 61

Silica, K, Na, Mg, Ca, Cl, CO3, SO4

Front 62

water + carbon dioxide yields ___

Back 62

carbonic acid

Front 63

water + sulfur yields ____

Back 63

sulfuric acid

Front 64

what is effective at breaking down minerals

Back 64

H+

Front 65

Goldrich Stability Series

Back 65

minerals that form last in Bowen's Reaction are the last to weather. (form at conditions most to earth's surface)

Front 66

Biological Weathering

Back 66

chemical and/or mechanical in nature
roots split rocks apart
roots produce acids that dissolve rocks
trees grow
burrowing animals

Front 67

The four classes of sedimentary rock:

Back 67

Clastic
Biochemical
Organic
Chemical

Front 68

Clastic rock

Back 68

loose rock fragments (clasts) cemented together

Front 69

Biochemical rock

Back 69

cemented shells of organisms

Front 70

Organic rocks

Back 70

carbon-rich remains of once living organisms

Front 71

Chemical rocks

Back 71

minerals that crystallize directly from water

Front 72

Physical and chemical weathering provide ___ ____ for all sedimentary

Back 72

raw material

Front 73

Clastic sedimentary rocks are created by

Back 73

Weathering: generation of detritus via rock disintegration.
Erosion: removal of sediment grains from parent rock.
Transportation: dispersal by gravity, wind, water, and ice
Deposition: settling out of the transporting fluid
lithification: transformation into solid rock

Front 74

Lithification

Back 74

transforms loose sediment into solid rock.

Front 75

Compaction (lithification)

Back 75

burial adds pressure to sediment
squeezes out air and water
compresses sediment grains

Front 76

Cementation (lithification)

Back 76

minerals grow in pore spaces.
often quartz or calcite
Precipitate from groundwater
Glue sediments together.

Front 77

Clastic Rocks are classified on the basis of

Back 77

texture and composition
Clast (grain) size
clast composition
angularity and sphericity
sorting
character of cement
there is a diversity of clastic rocks

Front 78

Sphericity-

Back 78

degree to which a clast nears a sphere

Front 79

Fresh detritus is usually ____ and ____

Back 79

angular and nonspherical

Front 80

Grain ____ and ____ increases with transport

Back 80

roundness and sphericity

Front 81

Well-rounded clasts mean

Back 81

that they have transported long distances

Front 82

Angular clasts

Back 82

negligible transport

Front 83

Biochemical Rocks

Back 83

Sediments derived rom the shells of living organisms
Hard mminieral skeletons accumulate after death
Different sedimentary rocks are made from these materials.

Front 84

Calcite and Argonite (CaCO3)

Back 84

limestone

Front 85

Silica (SiO2)

Back 85

chert

Front 86

Organic Sedimentary rocks

Back 86

coal- altered remains of fossil vegetation
black, combustible sedimentary rock
over 50-90% carbon
fuels industry since the beginning of the industrial revolution

Front 87

Cross beds

Back 87

created by ripple and dune migration
Sediment moves up the gentle side or a ripple or dune
Sediment piles up, then slips down the steep face
The slip face continually moves downcurrent
Added sediment forms sloping cross beds

Front 88

two ways of dating geological materals

Back 88

relative ages and numerical ages

Front 89

Relative age

Back 89

based upon order of formation
qualitive method developed hundred of years ago
Permit determination of older vs. younger relationships

Front 90

Numerical ages

Back 90

actual number of years since an event.
Quantitative method developed recently.

Front 91

____ are used to establish relative dating ( relative sequence of events)

Back 91

Principles of Geology

Front 92

Who came up with the principle of uniformitarianism

Back 92

James Hutton

Front 93

principle of uniformitarianism

Back 93

the present is key to the past
processes seen today are the same as those of the past.
Geologic change is slow, large changes require a long time
therefore, there must have been a long time before humans

Front 94

The principle of original horizontality

Back 94

sediments settle out of a fluid by gravity
this causes sediments to accumulate horizontally
sediment accumulation is not favored on a slope
tilted sedimentary rocks must be deformed

Front 95

The principle of superposition

Back 95

In an undeformed sequence of layered rocks:
each bed is older than the one abouve and younger than the one below.
Younger strata are on top, older strata on bottom

Front 96

The principle of lateral continuity

Back 96

Strata often form latterly extensive horizontal sheets.
Subsequent erosion dissects once- countinuous layers.
Flat-lying rock layers are unlikely to have been disturbed.

Front 97

The principle of cross-cutting relations

Back 97

Younger features truncate (cut across) older features.
Faults, dikes, erosion, must be younger than the material that is faulted, intruded, or eroded.
A volcano cannot intrude rocks that aren't there

Front 98

Principle of inclusions

Back 98

a rock fragment within another
are always older than the enclosing material.
weathering ruble must have come from older rock.
Fragments (xenoliths) are older than igneous intrusion.

Front 99

Principle of Faunal Succession (aka Fossil Succession)

Back 99

Fossiles are often preserved in sedimentary rocks
are time markers useful for relative age-dating
speak of past depositional environments
Specific fossils are only found within a limited time range

Front 100

Fossil range

Back 100

the first and last appearance

Front 101

Each fossil has a unique

Back 101

range

Front 102

Range ovelap

Back 102

narrows time

Front 103

Index fossils

Back 103

diagnositc of a particular geological time

Front 104

Fossils correlate strata

Back 104

locally
regionally
Globally

Front 105

unconformity

Back 105

is a gap in the rock record

Front 106

what causes unconformity

Back 106

erosion and nondeposition

Front 107

who was the first to recognize the significance in unconformity

Back 107

JAmes hutton

Front 108

types of unconformity

Back 108

Angular
non
dis

Front 109

Angular unconformity

Back 109

huge gap in time
horizontal marine sediments deformed by orogenesis
mountains eroded completely
renewed marine invasion
new sediments deposited

Front 110

Nonconformity

Back 110

igneous/metamorphic rocks capped by sedimentary rocks
Igneous or metamorphic rocks were exposed by erosion.
Sediment was deposited on this eroded surface

Front 111

Disconformity

Back 111

parallel strata bounding nondeposition
Due to an interruption in sedimentation
Pause in deposition
Sea level falls, then rises
Erosion
Often hard to recognize

Front 112

what describes the sequence of strata

Back 112

a stratigraphic column

Front 113

Stratigraphic column

Back 113

Formations can be traces over long distances
Contacts define boundaries between formations or beds
Several formations may be combined as group

Front 114

Lithologic correlation

Back 114

based on rock type: is regional
Sequence is the relative order in which the rocks occur
Marker beds have unique characteristics to aid correlation.

Front 115

Fossil correlation

Back 115

is based on fossils within rocks
applicable to much broader areas

Front 116

Geologic time scale

Back 116

earth's calendar

Front 117

Eon's

Back 117

largest subdivision of time (hundreds to thousands of Ma)

Front 118

Era's

Back 118

subdivisions of an eon (65 to hundreds Ma)

Front 119

Periods

Back 119

subdivisions of an era (2-70 Ma)

Front 120

Epochs

Back 120

subdivisions of a period (.011 to 22 Ma)
smallest

Front 121

Names

Back 121

Cenozoic
Mesozoic
Paleozoic

Front 122

Cenozoic

Back 122

recent life

Front 123

Mesozoic

Back 123

middle life

Front 124

Paleozoic

Back 124

Ancient Life

Front 125

Numerical ages give ages of rocks in

Back 125

years
based on radioactive decay of atoms in minerals
radioactive decay proceeds at a known, fixed rate
radioactive elements act as internal clocks
(geochronology)

Front 126

Isotopes

Back 126

elements that have varying numbers of neutrons

Front 127

isotopes have similar

Back 127

mass numbers

Front 128

Stable isotopes

Back 128

isotopes that never change
Carbon 13

Front 129

Radioactive isotopes

Back 129

spontaneously decay
Carbon 14
progresses along a decay chain

Front 130

Decay chain

Back 130

decay creates new unstable elements that also decay
decay proceeds to a stable element endpoint

Front 131

Parent isotopes

Back 131

the isotope that undergoes decay

Front 132

Daughter isotope

Back 132

product of parent decay

Front 133

Half-life

Back 133

the time for half of the unstable nuclei to decay
the half-life is a characteristic of each isotope
after one t 1/2, one-half of the original parent remains
ie 50% goes to 25%, 25% goes to 12.5 % etc.
after 3 t 1/2, one-eighth of the original parent remains
as the parent disappears, the daughter "grows in"

Front 134

Numerical ages are possibe without isotopes

Back 134

Growth rings- annual layers from trees or shells
Rhythmic layering- annual layers in sediments or ice.

Front 135

age of the earth based off of what

Back 135

4.57 Ga
moon rocks and metorites

Front 136

With the respect to sed record, unformities represent a _____ in geologic time

Back 136

hiatus

Front 137

True or False: Sedimentary rocks cannot be directly dated

Back 137

true

Front 138

Isotope dating gives the time a mineral cooled below it's

Back 138

closure temperature